Silent Witnesses (11 page)

On the evening of January 2, 1933, Zemenides was at his lodgings in Hampstead and had settled in for the evening. Around 11:20
PM
there was a knock on the front door of the lodgings. It was answered by another resident, a Mr. Deby. The man at the door asked to speak to Dr. Zemenides and Deby allowed him in. A few minutes later there was the sound of a struggle followed by several shots. The man Deby had admitted fled into the night. Zemenides was found inside his room. He had been shot dead.

Given the circumstances, Petrou was an obvious suspect. The police took him into custody. When they searched the cellar where Petrou lodged, they recovered a .32 self-loading Browning pistol with five cartridges still in the magazine. Two of these cartridges were standard self-loading pistol cartridges, rimless with nickel-jacketed bullets; the other three were .32 revolver cartridges with the rims filed off and with lead bullets. A search of the crime scene resulted in the recovery of two fired cartridge cases, one a rimless self-loading pistol cartridge, the other a .32 revolver cartridge with the rim filed down. The bullet removed from Zemenides's body was a nickel-jacketed pistol bullet. A second projectile recovered from the panelling at the scene of the murder was found to be a lead revolver bullet. It was assumed by the investigating team that the recovered bullets had been fired by the gun found at Petrou's lodgings.

The defense retained the services of Major Sir Gerald Burrard, who, like the famous Churchill, was one of the country's leading firearms experts. With the assistance of the handgun expert Dr. R. K. Wilson, he began work on the cartridge cases. After lengthy detailed examination, the two ballistics experts finally managed to demonstrate that the gun found at Petrou's lodgings could not have been the murder weapon, because the bullets removed from the body and those found at the scene did not match. The jury were convinced by this evidence and returned a “not guilty” verdict. The real killer was never discovered and the crime remains unsolved. The circumstantial evidence against Petrou was strong and, had it not been for the ballistic evidence supplied by Burrard and Wilson, he might well have been hanged for a crime he did not commit.

The invention of guns not only revolutionized warfare but also made the job of the criminal a great deal simpler—a person can easily carry a concealed pistol, making it a convenient and horribly efficient way to kill. In the modern world more people are murdered by handguns than by any other single means. The analysis of bullets and weapons is therefore a necessary and often extremely significant forensic skill. However, as with so much forensic science, it is a game of cat and mouse—as soon as the scientists solve one problem, the criminals will become aware of their progress and react accordingly. Ensuring that no shell cases are left lying around, making sure that the bullet shatters on impact, and destroying the gun after use are all methods employed by criminals today in order to hide their tracks. It's an ongoing battle, but one that forensic scientists remain determined to win.

Yet who would have thought the old man to have had so much blood in him?

William Shakespeare,
Macbeth
(c. 1606)

A
ddine G. Erskine commented in his book
The Principles and Practice of Blood Grouping
that “for at least as long as recorded history, man has been interested in and mystified by blood.” It's true that there can be few substances that carry such symbolic weight: blood sustains life, but since it is only ever seen when a body has been damaged, paradoxically we also associate it strongly with death. Since violent crime almost inevitably results in blood being spilled, it is perhaps unsurprising that the study of blood has long been one of the most important aspects of forensics.

That said, it wasn't until the early part of the twentieth century that blood analysis began to play a really significant part in crime investigation (see
Plate 6
). Prior to that time the knowledge it was possible to gain from analyzing blood was limited; there wasn't even a method for distinguishing human blood from animal blood
until 1901. An incident in Scotland in 1721 serves to illustrate the problems that could arise as a result of this lack of knowledge.

William Shaw lived in Edinburgh. He had a daughter named Catherine, though it was widely known that he wasn't on the best of terms with her, largely because he disapproved of the man she had been seeing. One evening, neighbors living within the same tenement heard a violent argument going on in the rooms where the Shaws lived. It concluded with several groans and the sound of a door slamming, followed by silence.

Concerned, the neighbors decided to knock to check that all was well. When there was no reply, they sent for the police, who forced open the locked door upon arrival. Inside they were greeted with a terrible scene: Catherine Shaw was lying in a pool of blood, a bloody knife at her side. She was still alive but unable to speak. However, when asked if her father was responsible for her present condition, she nodded her head. She died shortly afterwards without being able to give a fuller account of what had occurred.

A little later, Shaw returned to the flat. The police found bloodstains on his clothing and arrested him immediately. He was charged with the murder of his daughter soon afterward. In his defense he said that Catherine had committed suicide out of despair at being unable to be with the man she loved (because of his refusal to allow them to marry). He admitted that they had argued, fiercely, but he said that he had not harmed her, having stormed out of the room in a rage. He further claimed that the blood discovered on his clothes was his own, saying that he had cut himself a few days before and that the bandage had come loose, letting blood drip onto his clothes. However, the jury was not impressed by this explanation and Shaw was found
guilty and sentenced to death. He was hanged in November 1721, still protesting his innocence to the last.

Considering that both father and daughter were dead, one would expect that to be the end of the matter. However, the next tenant to move into the flat discovered a letter in a small opening near the chimney. When it was opened and read, it turned out to be a suicide note from Catherine. She said she had decided to kill herself because her father would not allow her to marry the man she loved and concluded by saying that, as a result, he was the cause of her death. When the letter was examined and its authenticity established, the authorities realized they had hanged an innocent man. William Shaw's body was cut down from the chains in which it had been hung and he was given a Christian burial—the very least that could be done for him.

Today it is unlikely that a miscarriage of justice such as this could occur: modern science enables us to establish a blood type, so it would be possible to verify that the blood on Shaw's clothes was indeed his own and so confirm the truth of his story, or at least that part of it. However, in 1721 such technology was still a long way off.

The first really significant advance in blood analysis was made in 1853 by the Polish physician Ludwig Teichmann. He developed a test to confirm the presence of blood which, though complex, was nonetheless effective. He discovered that if you dissolved a sample of dried blood in a mixture of saltwater and glacial acetic acid, then warmed the mixture, microscopic prismatic crystals would form; a substance he called hematin. A version of this test is still used today to identify whether dried stains found at a crime scene contain blood.

Hematin extracted from the blood of cattle; the crystalline structure which Teichmann observed is visible.

A decade later the German chemist Christian Friedrich Schönbein—who is also the discoverer of ozone and the inventor of the fuel cell—discovered that hydrogen peroxide will foam in the presence of blood. Even a tiny amount sets off this reaction. The downside was that the same thing happens with small amounts of semen, saliva, rust, and some kinds of boot polish, since all these substances contain specific enzymes that cause the oxidation of hydrogen peroxide. Despite this drawback, Schönbein's test was still useful, as it provided a quick way of eliminating suspicious stains—if the hydrogen peroxide did not foam, then you at least knew that blood was not present, and if it did then you knew that further investigation was required.

Other scientists continued to work on the same problem, and by the end of the nineteenth century there was a wide array of tests to detect the presence of blood. However, there was still no
test that differentiated between human and animal blood. In 1841 a French chemist named Barruel believed he had cracked this problem; he claimed that when heated with sulphuric acid, human blood gave off a specific “sweat” odor that was unique to it. Some Paris courts were convinced by Barruel's claims and allowed information derived from his methods into evidence. Unfortunately his theory had no basis whatsoever in fact. In 1850, Ludwig Teichmann also thought he had found a solution to the puzzle when he developed a test based on the shape of blood crystals. Unfortunately, as well as being rather complicated, this test was fairly prone to error and was therefore of very limited practical use.

Extraordinarily it was Sir Christopher Wren (1632–1723), the architect of St. Paul's Cathedral and many other magnificent buildings, who, many years before, had paved the way for the mystery to be solved. He had studied at Oxford University and was a respected scientist. In 1656 he invented the intravenous injection. The syringe he used was a quill with a sharp point attached to a bladder. Instead of the device piercing the skin, an incision had to be made to make the vein available—as basic as it comes (and certainly not for the squeamish), but it worked.

The hypodermic syringe, as we recognize it, did not appear until 1853 (Dr. Alexander Wood of the Royal College of Physicians of Edinburgh is generally credited with its development), but the existence of crude syringes meant that in 1814 Dr. James Blundell (1791–1878) was able to start experimenting with blood transfusions. The first transfusions had already occurred in 1667 in Paris, performed by Jean-Baptiste Denys (1643–1704). Although Denys believed that transfusions should be performed using human blood, he decided to use animal blood, as he considered the risk to the blood donor was too
high. His transfusions therefore had fatal results, which led to the practice being banned in France and England. It was Blundell who reintroduced it. Blundell was fascinated to discover that he could almost drain a dog's blood before reviving it with the blood from another dog. If, however, he used the blood from a creature of a different species, such as a sheep, the dog died. By 1818 Blundell was trying blood transfusions on human patients but was unable to understand why some lived while others died after receiving the same treatment.

It was German physiologist Leonard Landois (1837–1902) who came up with a partial explanation for this. He observed that if red blood cells from one animal were mixed with the serum—the liquid base of blood in which the cells are suspended—of an animal of a different species, the red cells clumped together like lumps in porridge, and on occasion even burst. It was clear that if this reaction occurred in the human body, it would result in fatal illness.

However the breakthrough finally came when Karl Landsteiner (1868–1943), then an assistant professor at the Institute of Pathology and Anatomy in Vienna, published a paper in the
Vienna Clinical Weekly
entitled “On Agglutination Phenomena of Normal Human Blood.” The paper described the results of experiments he had done using his own blood along with that of several colleagues. In these experiments he found that mixing blood serum from one human being with the blood serum from another would sometimes produce the same “clumping” reaction or (to use the proper scientific term) agglutination. But the questioned remained—why?

He concluded that as some blood samples caused other blood samples to clump together, there must exist at least two “antigens,” which he named anti-A and anti-B. Blood serum
contains specific antibodies that react with different types of antigen. In fact, Landsteiner eventually concluded that there were four blood types, which he named A, B, AB, and O. The letters indicate the different types of antigen (which are a kind of protein) found on the surface of red blood cells of different types. Type A blood cells have the A antigen, type B have the B antigen, type AB have both, and type O have no antigens. Blood serum contains specific antibodies that react with different types of antigen. As a result, type A serum (or rather the antibodies within it) will agglutinate type B blood and type B serum will agglutinate type A blood. Type AB will agglutinate both type A and type B. However as type O has no antigens, it can be mixed safely with any serum type. It is only safe to give a patient a transfusion of blood if it is of a type that does not agglutinate with their own.